Answer:
In the Bible, the word leprosy is mentioned upwards of 40 times, depending on the Bible version being used. Leprosy was common in Bible times, and the many references to it were well understood by those who lived in unsanitary conditions. The main reason why leprosy is talked about so much in the Bible is that it is a graphic illustration of sin’s destructive power. In ancient Israel leprosy was a powerful object lesson of the debilitating influence of sin in a person’s life.

God had given the Israelites very specific instructions on how to deal with leprosy and other skin infections (Leviticus 13). Anyone suspected of having this disease had to go to a priest for examination (Leviticus 13:2-3). If found to be infected, “the leprous person who has the disease shall wear torn clothes and let the hair of his head hang loose, and he shall cover his upper lip and cry out, ‘Unclean, unclean.’ He shall remain unclean as long as he has the disease. He is unclean. He shall live alone. His dwelling shall be outside the camp” (Leviticus 13:45-46). The leper then was considered utterly unclean—physically and spiritually.

Incurable by man, many believed God inflicted the curse of leprosy upon people for the sins they committed. In fact, those with leprosy were so despised and loathed that they were not allowed to live in any community with their own people (Numbers 5:2). Among the sixty-one defilements of ancient Jewish laws, leprosy was second only to a dead body in seriousness. A leper wasn’t allowed to come within six feet of any other human, including his own family. The disease was considered so revolting that the leper wasn’t permitted to come within 150 feet of anyone when the wind was blowing. Lepers lived in a community with other lepers until they either got better or died. This was the only way the people knew to contain the spread of the contagious forms of leprosy.

The Bible records the story of a leper who was the first to be healed by Jesus (Matthew 8:2-4). The key lesson to be learned from this incident is that sin defiles us in the sight of God, but through Christ, we can be healed of the plague of sin that separates us from God. God loathes sin; it is repulsive to Him. Sin bans us from the presence of God because God will not allow sinful man in His sight and presence (Psalm 5:5; Habakkuk 1:13; Revelation 21:27). This is not only true of sins with a sexual connotation that are normally regarded as filthy and repulsive, but it includes all forms of disobedience and rebellion (1 Samuel 15:23; Proverbs 15:9). All sin is abhorrent to God. But those who have been redeemed from sin by grace through faith in Christ (Ephesians 2:8-9) can stand in God’s presence in full confidence that we are accepted “in the Beloved,” and we praise Him for the grace He extends to us for that purpose (Ephesians 1:5-7).

When we’ve captured a glimpse of the holiness and purity of God, we have to exclaim as did the prophet Isaiah, “Woe to me … I am ruined! For I am a man of unclean lips, and I live among a people of unclean lips, and my eyes have seen the King, the LORD Almighty” (Isaiah 6:5). Our attitude toward sin in the light of our Savior should echo the words of Peter: “Go away from me, Lord; I am a sinful man!” (Luke 5:1-8). Another key lesson we learn from the leper in Matthew’s Gospel is that just as the leper did, we can confidently approach Jesus in all our need, with all our sin and defilement. When we plead for cleansing and forgiveness, He will not turn us away (Hebrews 4:16; Psalm 103:12).